SEPARATION OF THE ROTATIONAL ISOMERS OF TETRAKIS(N-METHYL-2-PYRIDINIUMYL)PORPHYRIN AND CRYSTAL-STRUCTURE OF (TETRAKIS(N-METHYL-2-PYRIDINIUMYL)PORPHYRIN)COPPER HEXACYANOFERRATE

The rotational isomers of tetrakis(N-methyl-2-pyridiniumyl)porphyrin ( M(T(2-NMePyP4+); M = Zn-II, Cu-II, and Ni-II) have been separated and isolated as stable solids. The H-1 NMR resonances of the N-methyl grou ps are diagnostic of the rotational disposition of the neighboring N-m ethylpyridiniumyl groups. The crystal structure of 2O)T(2-NMePy)P][HFe II(CN)(6)][H2FeII(CN)(6)](0.5). 15H(2)O (R = 8.53%, R(w) = 9.25%, C2/c , Z = 4, a = 20.756(3) Angstrom, b = 21.311(3) Angstrom, c = 30.109(4) Angstrom, P = 102.79(3)degrees) shows that the Cu-II is five-coordina te with an axial water. The porphyrins are stacked in a regular sandwi ch array, with the faces having three positive charges bracketing wate r-rich regions in the structure, while the faces with one positive cha rge form loose, slipped porphyrin dimers (interporphyrin distance, 3.8 5 Angstrom. There are two types of protonated ferrocyanide anions-one (1/2 per porphyrin unit) embedded in the water-poor region and the oth er (1 per porphyrin unit) forming dimers linked by hydrogen-bonded wat ers in the water-rich regions of the structure. The positions of sever al crystal water oxygens suggest that the two types of ferrocyanide un its are linked via hydrogen-bonded waters.